Method and apparatus of controlling periodic CSI reporting

ABSTRACT

Exemplary embodiments of the present invention relates to an apparatus and method for performing periodic CSI reporting available in a system supporting a TDD-FDD aggregation operation and an FDD-TDD aggregation operation. A periodicity and an offset for periodic reporting of channel quality indicator and precoding matrix indicator may be determined based on the cell type of a primary serving cell for a TDD-FDD carrier aggregation and an FDD-TDD carrier aggregation.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of Korean PatentApplication No. 10-2013-0132101, filed on Nov. 1, 2013, which is herebyincorporated by reference in its entirety.

BACKGROUND

1. Field

The present disclosure relates to a wireless communication, morespecifically a method and apparatus of periodic channel stateinformation reporting applicable to a system supporting TDD (TimeDivision Duplex)-FDD (Frequency Division Duplex) joint operation.

2. Discussion of the Background

A wireless communication system may support Frequency Division Duplex(FDD) scheme and Time Division Duplex (TDD) scheme. In the FDD scheme,an uplink transmission and a downlink transmission may be simultaneouslyperformed in a cell because a carrier frequency for an uplink (UL)transmission is different from a carrier frequency for a downlink (DL)transmission exists. In the TDD scheme, with respect to one cell, anuplink transmission and a downlink transmission are distinguished fromeach other based on different time slots. In the TDD scheme, a basestation and a user equipment perform switching operations between atransmission mode and a reception mode because the same carrier is usedfor both an uplink transmission and a downlink transmission. In the TDDscheme, a Special Subframe may be added to provide a guard time forswitching between the transmission mode and the reception mode. TheSpecial Subframe may include Downlink Pilot Time Slot (DwPTS), GuardPeriod (GP), and Uplink Pilot Time Slot (UpPTS). According to the TDDscheme, resource amounts for the uplink transmission and resourceamounts for the downlink transmission may be asymmetrically assignedthrough various uplink (UL)-downlink (DL) configurations.

Currently, remaining frequency resources are scarce and varioustechnologies have been utilized in wide frequency bands because of thefrequency resource scarcity. For this reason, in order to provide awideband bandwidth for supporting higher data-rate requirements, each ofscattered bands has been configured to satisfy basic requirements tooperate an independent system and a carrier aggregation (CA) scheme,which aggregates various frequency bands into one system, has beenadopted. Here, each frequency band or carrier capable of an independentoperation may be defined as a component carrier (CC).

Further, a wireless communication system uses a link adaption in orderto make the maximum use of a given channel capacity, to controlModulation and Coding Scheme (MCS) and Transmission Power according to agiven channel. Here the link adaptation means changing modulation andchannel coding scheme depending on a wireless link condition to optimizethe communication performance To perform this link adaptation at a basestation, the periodic feedback of channel status information by aterminal is required, and the terminal carries out the periodic channelstatus reporting for it.

Recently, considered is a TDD-FDD joint operation technique supportingthe CA of an FDD band (or carrier) and a TDD band (or carrier) and/or adual connectivity thereof. A terminal supporting TDD-FDD joint operationmay be configured with a TDD serving cell and an FDD serving cellsimultaneously. However, the existing periodic channel status reportingmethod assumes only the periodic channel status reporting in case that aterminal is configured with a single serving cell, or the terminal isconfigured with an FDD or a TDD type serving cell; it does not considerthe case that a TDD serving cell and an FDD serving cell are configuredat the terminal. Therefore, there exists a need for a method of aperiodic channel status reporting for a terminal configured with TDD-FDDjoint operation.

SUMMARY

An exemplary embodiment of the present invention provides a method andapparatus for a periodic CSI transmission in a wireless communicationsystem.

An exemplary embodiment of the present invention provides a method andapparatus for a periodic CSI reporting for a terminal configured withTDD-FDD joint operation.

An exemplary embodiment of the present invention provides a method ofconfiguring a periodicity value for a periodic CSI reporting on aserving cell when TDD-FDD joint operation is configured at a terminal.

A terminal supporting a periodic Channel Quality Indicator(CQI)/Precoding Matrix Index (PMI) reporting is provided in a wirelesssystem capable of the carrier aggregation (CA) of an FDD-based firstserving cell and a TDD-based second serving cell. The terminal includesa receiver to receive TDD-FDD CA configuration information for the CA ofthe first serving cell and the second serving cell, and to receive aparameter about the periodic CQI/PMI reporting point of time of thefirst serving cell or the second serving cell, a RRC processing part toconfigure the CA of the first serving cell and the second serving cellat the terminal based on the TDD-FDD CA configuration information, andto detect a period and offset for a periodic CQI/PMI reporting of thefirst serving cell or the second serving cell based on the parameterabout the periodic CQI/PMI reporting point of time, and a transmittingunit to transmit the CQI/PMI reporting to a base station based on thedetected period and an offset.

According to an aspect of the present invention, in a wirelesscommunication system supporting the CA of an FDD-based first servingcell and a TDD-based second serving cell, provided is a base stationwhich supports a periodic CQI/PMI reporting. The base station includes atransmitting unit to transmit TDD-FDD CA configuration information forthe CA of the first serving cell and the second serving cell to aterminal, and to transmit a parameter about the periodic CQI/PMIreporting point of time of the first serving cell and the second servingcell, a RRC processing part to detect a period and an offset for theperiodic CQI/PMI reporting of the first serving cell and the secondserving cell based on the parameter about the periodic CQI/PMI reportingpoint of time, and a receiver to receive the periodic CQI/PMI reportingbased on the detected period and offset.

According to an aspect of the present invention, in a wirelesscommunication system supporting the CA of an FDD-based first servingcell and a TDD-based second serving cell, a method of periodic CQI/PMIreporting is provided. The method comprises receiving TDD-FDD CAconfiguration information for the CA of the first serving cell and thesecond serving cell, CA configuring the first serving cell and thesecond serving cell at the terminal based on the TDD-FDD CAconfiguration information, receiving the parameter about the periodicCQI/PMI reporting point of time of the first serving cell and the secondserving cell, detecting the period and the offset for the periodicCQI/PMI reporting of the first serving cell and the second serving cellbased on the parameter about the periodic CQI/PMI reporting point oftime, and transmitting the periodic CQI/PMI reporting to a base stationbased on the detected period and the offset.

According to aspects, when a terminal is configured with TDD-FDD carrieraggregation (or dual connectivity), a smooth data transmission/receptionbetween a terminal and a base station may be provided through theconfiguration of the periodicity value for an effective periodic CSIreporting to a secondary serving cell.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication system according to anexemplary embodiment of the present invention.

FIG. 2 illustrates an example of a protocol structure to support amultiple carrier system according to an exemplary embodiment of thepresent invention.

FIG. 3 is an example of a radio frame structure according to anexemplary embodiment of the present invention. This is an FDD radioframe structure and a TDD radio frame structure.

FIG. 4 illustrates an example of a deployment scenario to which eIMTA isapplied.

FIG. 5 illustrates an exemplary embodiment of FDD-TDD joint operationtechnique that may be applicable to an exemplary embodiment of thepresent invention.

FIG. 6 illustrates examples of terminal capabilities for TDD-FDD jointoperation that may be applicable to an exemplary embodiment of thepresent invention.

FIG. 7 is a flow chart of CQI/PMI reporting between a terminal and abase station according to an exemplary embodiment of the presentinvention.

FIG. 8 is a block diagram illustrating a terminal and a base station inaccordance with an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Exemplary embodiments of the present invention will be described morefully hereinafter with reference to the accompanying drawings, in whichexemplary embodiments of the invention are shown. Throughout thedrawings and the detailed description, unless otherwise described, thesame drawing reference numerals are understood to refer to the sameelements, features, and structures. In describing the exemplaryembodiments, detailed description on known configurations or functionsmay be omitted for clarity and conciseness.

Further, the terms, such as first, second, A, B, (a), (b), and the likemay be used herein to describe elements in the description herein. Theterms are used to distinguish one element from another element. Thus,the terms do not limit the element, an arrangement order, a sequence orthe like. It will be understood that when an element is referred to asbeing “on”, “connected to” or “coupled to” another element, it can bedirectly on, connected or coupled to the other element or interveningelements may be present. In contrast, when an element is referred to asbeing “directly on,” “directly connected to” or “directly coupled to”another element, there are no intervening elements present.

Further, the description described herein is related to a wirelesscommunication network, and an operation performed in a wirelesscommunication network may be performed in a process of controlling anetwork and transmitting data by a system that controls a wirelessnetwork, e.g., a base station, or may be performed in a user equipmentconnected to the wireless communication network.

FIG. 1 is a diagram illustrating a wireless communication systemaccording to an exemplary embodiment of the present invention.

According to FIG. 1, a wireless communication system 10 is widelydeployed in order to provide diverse telecommunication services, such asvoice and packet data. A wireless communication system includes at leastone base station 11 (BS). Each BS 11 provides telecommunication serviceto certain cells 15 a, 15 b, and 15 c. A cell may again be divided intomultiple sectors.

User equipment 12 (mobile station, MS) may be located at a certainlocation or mobile, and may also be referred to as different terms,including UE (user equipment), MT (mobile terminal), UT (user terminal),SS (subscriber station), wireless device, PDA (personal digitalassistant), wireless modem, terminal, and handheld device. A basestation 11 may also be referred to as eNB (evolved-NodeB), BTS (BaseTransceiver System), Access Point, femto base station, Home nodeB, andrelay. A cell inclusively refers to various coverage areas, such as megacell, macro cell, micro cell, pico cell, and femto cell.

Hereinafter, the term downlink refers to communication from a basestation 11 to a UE 12, and the term uplink refers to communication froma UE 12 to a base station 11. For downlink, a transmitter may be part ofa base station 11, and a receiver may be part of a UE 12. For uplink, atransmitter may be part of a UE 12 and a receiver may be part of a basestation 11. There is no limitation in the multiple access method appliedto a wireless communication system. Diverse methods can be used,including CDMA (Code Division Multiple Access), TDMA (Time DivisionMultiple Access), FDMA (Frequency Division Multiple Access), OFDMA(Orthogonal Frequency Division Multiple Access), SC-FDMA (SingleCarrier-FDMA), OFDM-FDMA, OFDM-TDMA, OFDM-CDMA. Uplink transmission anddownlink transmission can use either TDD (Time Division Duplex), whichuses different time locations for transmissions, or FDD (FrequencyDivision Duplex), which uses different frequencies for transmissions.

Carrier Aggregation (CA), which is also referred to as spectrumaggregation or bandwidth aggregation, supports multiple carriers. Eachindividual unit carrier, which is aggregated by carrier aggregation, isreferred to as Component Carrier (CC). Each component carrier is definedby bandwidth and center frequency. CA is introduced to supportincreasing throughput, to prevent cost increase due to the introductionof the wideband radio frequency and to ensure the compatibility with theexisting system. For example, if five component carriers are allocatedas granularity that has a carrier unit with 20 MHz bandwidth, it cansupport 100 MHz bandwidth at maximum.

CA can be divided as contiguous carrier aggregation, which is made amongcontinuous CCs, and non-contiguous carrier aggregation, which is madeamong non-continuous CCs. The number of carriers aggregated betweenuplink and downlink can be configured differently. It is referred to assymmetric aggregation when there are equal number of downlink CCs anduplink CCs, and it is referred to as asymmetric aggregation when thenumber of downlink CCs and the number of uplink CCs are not equal.

The size of component carriers (in other words, bandwidth) can bedifferent. For example, if five component carriers are used to form 70MHz band, 5 MHz component carrier (carrier #0)+20 MHz component carrier(carrier #1)+20 MHz component carrier (carrier #2)+20 MHz componentcarrier (carrier #3)+5 MHz component carrier (carrier #4) can beaggregated together.

Hereinafter, a multiple carrier system includes the system that supportscarrier aggregation. Contiguous CA and/or non-contiguous CA can be usedin the multiple carrier system; in addition, both symmetric aggregationand asymmetric aggregation can be used in the multiple carrier system aswell. A serving cell can be defined as a component frequency band basedon multiple CC system which can be aggregated by CA. A serving cell mayinclude a primary serving cell (PCell) and a secondary serving cell(SCell). A PCell means a serving cell which provides security input andNon-Access Stratum (NAS) mobility information on Radio Resource Control(RRC) establishment or re-establishment state. Depends on the capabilityof a user equipment, at least one cell can be used together with a PCellto form an aggregation of serving cells, the cell used with a PCell isreferred to as an SCell. An aggregation of serving cells whichconfigured for a user equipment may include one PCell, or one PCelltogether with at least one SCell.

Downlink component carrier corresponding to a PCell refers to Downlink(DL) Primary Component Carrier (PCC), and uplink component carriercorresponding to a PCell refers to Uplink (UL) PCC. In addition,downlink component carrier corresponding to a SCell refers to a DLSecondary Component Carrier (SCC), and an uplink component carriercorresponding to a SCell refers to a UL SCC. Only DL CC may correspondto a serving cell, or a DL CC and an UL CC together may correspond to aserving cell.

FIG. 2 is a diagram illustrating an example of a protocol structure forsupporting a multi-carrier system according to an exemplary embodimentof the present invention.

Referring to FIG. 2, common Medium Access Control (MAC) entity 210manages physical layer 220 which uses a plurality of carriers. The MACmanagement message, transmitting through a certain carrier, may beapplied to other carriers. That is, the MAC management message is amessage which controls other carriers including the certain carriermentioned above. A physical layer 220 may be operated by the TimeDivision Duplex (TDD) and/or the Frequency Division Duplex (FDD).

FIG. 3 is a diagram illustrating an example of a radio frame structureaccording to an exemplary embodiment of the present invention. Thediagram illustrates a FDD radio frame structure and a TDD radio framestructure.

Referring to FIG. 3, one radio frame includes 10 subframes, and onesubframe includes 2 consecutive slots.

In the FDD, both carrier used for UL transmission and carrier used forDL transmission exist, and UL transmission and DL transmission can beperformed simultaneously in one cell.

In the TDD, on one cell basis, UL transmission and DL transmission canalways distinguished in time. Because a same carrier is used for both ULtransmission and DL transmission, a base station and user equipmentrepeatedly switches between the transmission mode and the receptionmode. In the TDD, special subframe can be placed to provide a guard timewhich is for switing mode between the transmission and the reception.Special subframe, as shown, includes a downlink pilot time slot (DwPTS),a guard period (GP), and an uplink pilot time slot (UpPTS). The DwPTS isused in the UE for initial cell search, synchronization, or channelestimation. The UpPTS is used in the BS for channel estimation anduplink transmission synchronization of the UE. The GP is needed to avoidinterference between an uplink and a downlink, and during the GP, no ULtransmission and DL transmission occurs.

Table 1 shows an example of TDD UL-DL configuration of radio frame.UL/DL configuration defines reserved subframe for UL transmission orreserved subframe for DL transmission. That is, UL-DL configurationinforms the rules how the uplink and the downlink are allocated (orreserved) in every subframe of one radio frame.

TABLE 1 Uplink- Switch- downlink point Subframe number configurationperiodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U D S U U U 1 5 ms D S UU D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms  D S U U U D D D D D 410 ms  D S U U D D D D D D 5 10 ms  D S U D D D D D D D 6 5 ms D S U U UD S U U D

In Table 1, ‘ID’ denotes a DL subframe, ‘U’ denotes a UL subframe, and‘S’ denotes a special subframe. As shown to Table 2, subframe 0 and 5are always allocated to DL transmission, and subframe 2 is alwaysallocated to UL-transmission. As shown to Table 2, each UL-DLconfiguration has a different number and position of DL subframe and ULsubframe in one radio frame. Through diverse UL-DL configuration, theamount of resource allocated to UL/DL transmission can be givenasymmetrically. To avoid severe interference between UL and DL amongcells, neighboring cells generally have same UL-DL configuration.

The point changing from DL to UL or the point changing from UL to DL isreferred to the switching point. The switch-point periodicity, which iseither 5 ms or 10 ms, means a repeating period of the same chainingaspect between the UL subframe and DL subframe. For example, referringto the UL/DL configuration 0, subframe from 0 to 4 changes D→S→U→U→U,subframe from 5 to 9 changes, as same as before, D→S→U→U→U. Since onesubframe is 1 ms, the switch-point periodicity is 5 ms. That is, theswitch-point periodicity is shorter than the length of one radio frame(10 ms), the changing aspect in the radio frame is repeated for onetime.

The UL-DL configuration in above Table 1 can be transmitted from a basestation to a user equipment through system information. The base stationcan inform a UL-DL allocation status change in a radio frame to a UE bytransmitting the index of the UL-DL configuration whenever the UL-DLconfiguration changes. Or the UL-DL configuration can be controlinformation which is transmitted to every UE in the cell throughbroadcast channel.

Further, there are some physical channels utilized in a physical layer.

First, as a downlink physical channel, Physical Downlink Control Channel(PDCCH) informs a terminal of the resource allocation of Paging Channel(PCH) and Downlink Shared Channel (DL-SCH), and Hybrid Automatic RepeatRequest (HARQ) information. PDCCH can bear a uplink grant informing theterminal of the resource allocation of uplink transmission. PhysicalDownlink Shard Channel (PDSCH) is mapped DL-SCH. Physical Control FormatIndicator Channel (PCFICH) informs the terminal of the number of OFDMsymbols used in PDCCHs, and transmitted every subframe. Physical HybridARQ Indicator Channel (PHICH) is a downlink channel, which carries aHARQ ACK/NACK signal that is a response of the uplink transmission.

Next, as a uplink physical channel, Physical Uplink Control Channel(PUCCH) carries uplink control information such as Hybrid AutomaticRepeat request (HARQ) Acknowledgment (ACK)/Non-acknowledgment (NACK),channel status information (CSI) representing downlink channel status,including, Channel Quality Indicator (CQI), precoding matrix index(PMI), precoding type indicator (PTI), rank indication (RI), etc.Physical Uplink Shared Channel (PUSCH) carries Unlink Shared Channel(UL-SCH). Physical Random Access Channel (PRACH) carries a random accesspreamble.

CQI provides information about link adaptive parameter that a terminalcan support in a given time. CQI may indicate the data rate which may besupported by a downlink channel in light of the characteristic of aterminal receiver, SINR (signal to interference plus noise ratio) and soon. A base station may determine the modulation scheme (QPSK, 16-QAM,64-QAM, etc.) to be applied to downlink channel and coding rate usingthe CQI. CQI can be generated in various methods. For example, CQI maybe generated by the way of quantizing a channel condition itself tofeedback it, the way of calculating a SINR (signal to interference plusnoise ratio) to feedback it, the way of notifying the status, which isactually applied, such as MCS (Modulation Coding Scheme), and so on. Incase that CQI is generated based on MCS, MCS includes modulation schemeand coding scheme, and corresponding coding rate, etc.

PMI provides information about pre-coding matrix in a codebook basedpre-coding. PMI is related to MIMO (Multiple Input Multiple Output). InMIMO, the feedback of PMI is referred to as closed loop MIMO.

RI is information about rank (that is, the number of layers) recommendedby a terminal. That is, RI indicates the number of independent streamswhich are used for spatial multiplexing. RI is fed back only in casethat the terminal operates in MIMO mode which utilizes spatialmultiplexing. RI is always associated with one or more CQI feedback.That is, CQI which is fed back is computed with the assumption of aspecific RI value. RI is fed back fewer times because the rank of achannel changes more slowly than CQI in general. The period of RItransmission may be a multiple of a CQI/PMI transmission period. RI isgiven for entire system bandwidth while frequency selective RI feedbackis not supported.

CSI may be transmitted periodically in PUCCH in accordance with theperiod determined at an upper layer. The terminal may be configured halfstatically by an upper layer signal to feedback different CSI components(CQI, PMI, RI) periodically in PUCCH. At this point, the terminaltransmits the corresponding CSI according to the defined CSI modesdefined as the following table.

TABLE 2 PMI Feedback Type No PMI Single PMI PUCCH CQI Wideband Mode 1-0Mode 1-1 Feedback Type (wideband CQI) UE Selected Mode 2-0 Mode 2-1(subband CQI)

Further, a periodic CSI reporting mode in PUCCH is supported for each oftransmission mode as follows.

TABLE 3 transmission mode PUCCH CSI reporting modes transmission mode 1Modes 1-0, 2-0 transmission mode 2 Modes 1-0, 2-0 transmission mode 3Modes 1-0, 2-0 transmission mode 4 Modes 1-1, 2-1 transmission mode 5Modes 1-1, 2-1 transmission mode 6 Modes 1-1, 2-1 transmission mode 7Modes 1-0, 2-0 transmission mode 8 Modes 1-1, 2-1 terminal is configuredwith PMI/RI reporting; modes 1-0, 2-0 terminal is not configured withPMI/RI reporting transmission mode 9 Modes 1-1, 2-1 terminal isconfigured with PMI/RI reporting and the number of CSI-RS port isgreater than 1; modes 1-0, 2-0 terminal is not configured with PMI/RIreporting or the number of CSI-RS port is 1 transmission mode 10 Modes1-1, 2-1 terminal is configured with PMI/RI reporting and the number ofCSI-RS port is greater than 1; modes 1-0, 2-0 terminal is not configuredwith PMI/RI reporting or the number of CSI-RS port is 1

For the terminal configured in transmission modes 1-9, one periodic CSIreporting mode is configured in each of serving cell by upper layersignaling. For the terminal configured in transmission 10, one or moreperiodic CSI reporting modes are configured in each serving cell byupper layer signaling.

CSI report via PUCCH may be in various report types as follows accordingto CQI/PMI/RI transmission combination, and supported are period andoffset values distinguished depending on each report type (hereinafter,referred as CSI type or type in short).

Type 1: supports CQI feedback on subband selected by a terminal.

Type 1a: supports subband CQI and a second PMI feedback.

Type 2, 2b, 2c: supports wideband CQI and PMI feedback.

Type 2a: supports wideband PMI feedback.

Type 3: supports RI feedback.

Type 4: transmits wideband CQI.

Type 5: supports RI and wideband PMI feedback.

Type 6: supports RI and PTI feedback.

Period, N_(pd), and Offset N_(OFFSET,CQI) for CQI/PMI reporting aredetermined based on parameter cqi-pmi-Configindex(I_(CQI/PMI)). This isdefined as following Table 4 in case of FDD and is defined as followingTable 5 in case of TDD.

TABLE 4 I_(CQI/PMI) Value of N_(pd) Value of N_(OFFSET,CQI) 0 ≦I_(CQI/PMI) ≦ 1 2 I_(CQI/PMI) 2 ≦ I_(CQI/PMI) ≦ 6 5 I_(CQI/PMI −) 2 7 ≦I_(CQI/PMI) ≦ 16 10 I_(CQI/PMI −) 7 17 ≦ I_(CQI/PMI) ≦ 36 20I_(CQI/PMI −) 17 37 ≦ I_(CQI/PMI) ≦ 76 40 I_(CQI/PMI −) 37 77 ≦I_(CQI/PMI) ≦ 156 80 I_(CQI/PMI −) 77 157 ≦ I_(CQI/PMI) ≦ 316 160I_(CQI/PMI −) 157 I_(CQI/PMI) = 317 Reserved 318 ≦ I_(CQI/PMI) ≦ 349 32I_(CQI/PMI −) 318 350 ≦ I_(CQI/PMI) ≦ 413 64 I_(CQI/PMI −) 350 414 ≦I_(CQI/PMI) ≦ 541 128 I_(CQI/PMI −) 414 542 ≦ I_(CQI/PMI) ≦ 1023Reserved

TABLE 5 I_(CQI/PMI) Value of N_(pd) Value of N_(OFFSET,CQI) I_(CQI/PMI)= 0 1 I_(CQI/PMI) 1 ≦ I_(CQI/PMI) ≦ 5 5 I_(CQI/PMI −) 1 6 ≦ I_(CQI/PMI)≦ 15 10 I_(CQI/PMI −) 6 16 ≦ I_(CQI/PMI) ≦ 35 20 I_(CQI/PMI −) 16 36 ≦I_(CQI/PMI) ≦ 75 40 I_(CQI/PMI −) 36 76 ≦ I_(CQI/PMI) ≦ 155 80I_(CQI/PMI −) 76 156 ≦ I_(CQI/PMI) ≦ 315 160 I_(CQI/PMI −) 156 316 ≦I_(CQI/PMI) ≦ 1023 Reserved

cqi-pmi-ConfigIndex(I_(CQI/PMI)) is set by upper layer signal such asRRC signaling.

In the periodic CQI/PMI reporting for TDD, reporting period(N_(pd))value applied to serving cell c depends on TDD UL/DL configuration inprimary serving cell(Pcell).

In one example, all UL subframes within one radio frame are used forCQI/PMI reporting, and the reporting period of N_(pd)=1 is applicablefor serving cell c only if the TDD UL/DL configuration of the primaryserving cell belongs to {0, 1, 3, 4, 6}.

In another example, the reporting period of N_(pd)=5 is applicable forserving cell c only if the TDD UL/DL configuration of the primaryserving cell belongs to {0, 1, 2, 6}.

In other example, the reporting period of N_(pd)={10, 20, 40, 80, 160}is applicable for serving cell c with regard to any TDD UL/DLconfiguration in primary serving cell.

Further, enhanced Interference Management and Traffic Adaptation (eIMTA)technique exists for inter-base station interference control andadaptive traffic control. eIMTA technique provides dynamic change of TDDUL/DL configuration in a time domain depending on traffic orinterference environment. For example, a terminal configured with eIMTAmay TDD UL/DL configuration dynamically per subframe based on thereception of eIMTA-RNTI masked PDCCH.

FIG. 4 illustrates an example of deployment scenario to which eIMTA isapplied.

Referring to FIG. 4, a plurality of macro cells and small cells (e.g.,pico cells or femto cells) may be deployed contiguously with the samefrequency or the adjacent frequency. (a) is a deployment scenario inwhich multiple outdoor small cells utilize the same frequency band asthat of macro cells. (b) is a deployment scenario in which a pluralityof small cells use the same frequency band, macro cells uses frequencybands which is adjacent to the frequency bands used by small cells, allmacro cells have the same UL/DL configuration, and small cells canadjust UL/DL configuration.

In the above scenarios, small cells (e.g., pico cells or femto cells)except macro cell may be supported by the dynamic change of TDD UL/DLconfiguration for interference or traffic control.

When the dynamic change of TDD UL/DL configuration is supported asstated above, DL HARQ reference configuration (that is, DL referenceUL/DL configuration) for DL HARQ may be selected among TDD UL/DLconfiguration {2, 4, 5}.

In this case, a terminal may not expect in DL HARQ referenceconfiguration that any subframe which is configured as UL subframe orspecial subframe is used dynamically as DL subframe.

Recently, considered is a joint operation technique which supports (1)the CA (Carrier Aggregation) of FDD band or carrier with TDD band orcarrier and/or (2) dual connectivity.

FIG. 5 illustrates an example of FDD-TDD CA that may be applicable to anexemplary embodiment of the present invention.

Referring to FIG. 5, a legacy TDD terminal (520) may receive wirelesscommunication service only in TDD band, and legacy FDD terminal (540)may receive wireless communication service only in FDD band. On theother hand, FDD-TDD CA capable terminal (UE, 500) may receive wirelesscommunication service in FDD band and TDD band, and may receive CA basedwireless communication service simultaneously in TDD band carrier andFDD band carrier.

For the above TDD-FDD CA, the following exemplary deployment scenariosmay be considered.

In one example: an FDD base station and a TDD base station is co-locatedin the same area (for example, CA scenario 1 to 3), and the FDD basestation and the TDD station are not co-located in the same place butconnected via an ideal backhaul (CA scenario 4).

In another example: an FDD bas station and a TDD station are notco-located in the same area, and are connected via non-ideal backhaul(for example, small cell scenario 2a, 2b and macro-macro scenario).

Nevertheless, it is preferable that the TDD base station and FDD basestation are connected via the ideal backhaul for TDD-FDD CA, and a TDDcell and an FDD cell are synchronized to operate.

Further, the following prerequisites may be taken into consideration forTDD-FDD CA.

First, FDD-TDD CA capable terminals may access an FDD single modecarrier and a legacy TDD single mode carrier.

Second, legacy FDD terminals and TDD-FDD CA capable terminals may campon and connect with an FDD carrier that is a part of the joint-operatingFDD/TDD network.

Third, legacy TDD terminals and TDD-FDD CA capable terminals may camp onand connect with a TDD carrier which is a part of the joint-operatingFDD/TDD network.

Fourth, network architecture enhancement for facilitating FDD-TDD CA(e.g., for non-ideal backhaul, etc.) may be considered. However, itshould be considered to keep network architecture change at a minimumbecause it is still important from the operator's point of view.

Also, the following terminal capabilities may be considered when aterminal supports TDD-FDD CA.

FIG. 6 illustrates the examples of terminal capabilities for TDD-FDD CAthat may be applicable to an exemplary embodiment of the presentinvention. FIG. 6 shows examples for TDD-FDD carrier CA.

Referring to FIG. 6, (a) illustrates that a terminal supports thecarrier aggregation of a TDD carrier with an FDD carrier, (b)illustrates that a terminal supports the carrier aggregation of a TDDcarrier with an FDD downlink carrier, (c) illustrates that a terminalsupports the carrier aggregation of the downlink subframe in a TDDcarrier with an FDD carrier.

As stated above, a terminal may support various types of TDD-FDD CA, andmoreover, is capable of simultaneous reception in FDD and TDD carriers(that is, DL aggregation), and secondly, may carry out simultaneoustransmission in FDD and TDD carriers (i.e., UL aggregation), andthirdly, may carry out simultaneous transmission and reception in FDDand TDD carriers (i.e., full duplex).

In the above TDD-FDD CA, the maximum number of supported aggregationcomponent carriers (CCs) may be, for example, five (5). Further, theaggregation of different UL/DL configurations for TDD carriers indistinct bands may be supported.

In this case, an FDD-TDD CA capable terminal may support TDD-FDD DL CA,and may not support TDD-FDD UL CA. An FDD-TDD CA capable terminal maysupport at least TDD-FDD DL CA, while it may or may not support TDD-FDDUL CA.

On the one hand, a terminal may establish a dual connectivity via two ormore base stations among the base stations constituting at least oneserving cell. The dual connectivity is an operation that a correspondingterminal consumes radio resources provided by at least two distinctnetwork points (e.g., macro base station and small base station) in aRadio Resource Control Connected (RRC_CONNECTED) mode. In this case, theat least two distinct network points may be connected via a non-idealbackhaul. At this point, one the at least two distinct network pointsmay called macro base station (or master base station, or anchor basestation), and the others may be called small base stations (or secondarybase stations or assisting base stations or slave base stations).

A terminal may support a TDD-FDD joint operation if the terminal isconfigured with carrier aggregation (CA) and/or dual connectivity asdescribed above. However, the traditional periodic channel statusreporting method assumed the case that the terminal is configured with asingle serving cell, or FDD or TDD type serving cells, it doesn'tconsider the situation that a TDD serving cell and an FDD serving cellare configured with regard to the terminal Therefore, a periodic channelstatus reporting method for a terminal configured with TDD-FDD jointoperation is required. The following describes an exemplary embodimentof the invention assuming that the terminal is configured with CA;however, aspects of the present invention may be applied to the casethat the terminal is configured with dual connectivity.

A terminal configured with the existing, up to, Rel-11 could alwaystransmit Uplink Control Information (UCI) in PUCCH on primary servingcell (Pcell). However, the need for PUCCH transmission on a Secondaryserving cell (Scell) is growing as per the requirement of small cellenhancement and TDD-FDD CA, the PUCCH transmission carrying periodic CSIreporting may be conducted in Scell as well as Pcell. That is, whenTDD-FDD CA is configured the PUCCH transmission for periodic CSIreporting may be carried out in Pcell or Scell, and the serving cell inwhich PUCCH is transmitted may be called “PUCCH transmission servingcell.” Hereinafter, it is described assuming that the PUCCH transmissionserving cell is Pcell, however the PUCCH transmission serving cell maybe a Scell.

Case 1. FDD (Pcell)-TDD (Scell) CA

Case 1 is about the case that a terminal is CA configured with a Pcell,which is a PUCCH transmission serving cell, being configured with FDD,and a Scell being configured with TDD. In the current standard, when thePcell is configured with FDD as described above, there exists no methodof determining a periodicity value for a periodic CSI reporting by TDDbased Scell (N_(pd)). Thus, to support TDD-FDD CA, a method ofdetermining the periodicity value for periodic CSI reporting by TDDScell, this may follow the methods described as follows. Here the Scellor Pcell for the periodic CSI reporting may be called serving cell c.

A First Embodiment

In a first embodiment, a periodicity value for serving cell c (e.g.,Scell) may be applied based on the FDD configuration or TDD UL/DLconfiguration of the corresponding serving cell c regardless of Pcell.This can be shown as the below table.

TABLE 6 If a UE is configured with more than one serving cells and aprimary cell (i.e. PUCCH serving cell) is FDD (frame structure type 1),for periodic CQI/PMI reporting in a serving cell c which has the framestructure type 2 (TDD), the following periodicity values apply for theserving cell c: The reporting period of N_(pd) = 1 is applicable for theserving cell c only if TDD UL/DL configuration of the serving cell cbelongs to {0, 1, 3, 4, 6}, and where subframes of the primary cell inUL (i.e. PUCCH serving cell) which are corresponding to UL subframes ofthe serving cell c in a radio frame are used for CQI/PMI reporting. Thereporting period of N_(pd) = 5 is applicable for the serving cell c onlyif TDD UL/DL configuration of the serving cell c belongs to {0, 1, 2,6}. The reporting periods of N_(pd) = {10, 20, 40, 80, 160} areapplicable for the serving cell c for any TDD UL/DL configuration of theserving cell c.

Referring to Table 6, when terminal is configured with a plurality ofserving cells and the Pcell is FDD, the reporting periodicity value at aTDD serving cell c for periodic CQI/PMI is as follows. In one example,in one radio frame, the subframes of a primary serving cellcorresponding to the UL subframes of a serving cell c is used forCQI/PMI reporting, and the reporting period of N_(pd)=1 is applicablefor serving cell c only if the TDD UL/DL configuration of the servingcell c belongs to {0, 1, 3, 4, 6}. In another example, only when the TDDUL/DL configuration of the serving cell c belongs to {0, 1, 2, 6}, thereporting period of N_(pd)=5 is applicable for the serving cell c. In afurther example, for any TDD UL/DL configuration of the serving cell c,the reporting period of N_(pd)={10, 20, 40, 80, 160} is applicable forthe serving cell c.

Further, when eIMTA is enabled at the serving cell c, the TDD UL/DLconfiguration of the Scell may be replaced with or referred to a UL/DLconfiguration value configured via RRC signaling. In case, the reportingperiodicity value at a serving cell c for periodic CQI/PMI is determinedby the reference UL/DL configuration value configured via the RRCsignaling.

A Second Embodiment

In the second embodiment, the periodicity value for a serving cell c(e.g., Scell) is based on the above Table 4 which shows the mappingrelationship among I_(CQI/PMI), N_(pd) and N_(offset,CQI) for FDDbecause Pcell is FDD. That is, the periodicity value for a periodic CSIreporting of the TDD based serving cell c may be determined utilizingthe above Table 4 which is defined for FDD. This may be described as thefollowing Table 7 or Table 8.

TABLE 7 If a UE is configured with more than one serving cells and aprimary cell (i.e. PUCCH serving cell) is FDD (frame structure type 1),for periodic CQI/PMI reporting in a serving cell c (FDD or TDD), thefollowing periodicity values apply for the serving cell c: Theperiodicity N_(pd) is determined based on the parameter cqi-pmi-ConfigIndex (ICQI/PMI) given in Table 4 (Parameter from FDD)

TABLE 8 For a UE configured in transmission mode 1-9 and for eachserving cell, or for a UE configured in transmission mode 10 and foreach CSI process in each serving cell, the periodicity N_(pd) (insubframes) and offset N_(offset,CQI) (in subframes) for CQI/PMIreporting are determined based on the parameter cqi-pmi-ConfigIndex(I_(CQI/PMI)) given in Table 4 if the primary cell is FDD.

Referring to Table 7 to Table 8, a terminal is configured with multipleserving cells, and if a Pcell is FDD, the reporting periodicity value ina TDD or FDD serving cell c for periodic CQI/PMI reporting is determinedbased on cqi-pmi-ConfigIndex (I_(CQI/PMI)) value and the above describedTable 4 or Table 5.

Case 2. TDD(Pcell)-FDD(Scell) CA

Case 2 is the case that a terminal is CA configured with a Pcell whichis a PUCCH transmission serving cell being configured with TDD, and withScell being configured with FDD. In the current standard, when Pcell isconfigured with TDD as described above, there exists no method ofdetermining periodicity value for periodic CSI reporting of FDD basedScell (N_(pd)). Thus, a method of determining the periodicity value forperiodic CSI reporting of an FDD Scell to support TDD-FDD CA, and thismay follow the methods as follows. Here the Scell or the Pcell forperiodic CSI reporting may be referred to a serving cell c.

In the method, based on the TDD UL/DL configuration of the Pcell, theperiodicity value for the serving cell c (e.g., FDD Scell) is applied.The periodicity value for the serving cell c may be represented as thefollowing table. This includes both of the case where the serving cell cis FDD or TDD.

TABLE 9 If a UE is configured with more than one serving cells and aprimary cell (i.e. PUCCH serving cell) is TDD(frame structure type 1),for periodic CQI/PMI reporting in a serving cell c (FDD or TDD), thefollowing periodicity values apply for the serving cell c depending onthe TDD UL/DL configuration of the primary cell: The reporting period ofN_(pd) = 1 is applicable for the serving cell c only if TDD UL/DLconfiguration of the primary cell belongs to {0, 1, 3, 4, 6}, and whereall UL subframes of the primary cell in a radio frame are used forCQI/PMI reporting. The reporting period of N_(pd) = 5 is applicable forthe serving cell c only if TDD UL/DL configuration of the primary cellbelongs to {0, 1, 2, 6}. The reporting periods of N_(pd) = {10, 20, 40,80, 160} are applicable for the serving cell c for any TDD UL/DLconfiguration of the primary cell.

Referring to FIG. 9, in case that a terminal is configured with multipleserving cells and a Pcell is TDD, the reporting periodicity value to aserving cell c (FDD or TDD) for a periodic CQI/PMI is as follows. In oneexample, within one radio frame all subframes of the Pcell are used forthe CQI/PMI reporting, and the reporting period of N_(pd)=1 for theserving cell c is applicable only if the TDD UL/DL configuration of thePcell belongs to {0, 1, 3, 4, 6}. In another example, only if the TDDUL/DL configuration of the Pcell belongs to {0, 1, 2, 6}, the reportingperiod of N_(pd)=5 is applicable for the serving cell c. In furtherexample, for any TDD UL/DL configuration of the Pcell, the reportingperiod of N_(pd)={10, 20, 40, 80, 160} is applicable for the servingcell c.

Further, in case that the Pcell is eIMTA enabled, the TDD UL/DLconfiguration of the Pcell may be replaced with or referred to areference UL/DL configuration value configured through a RRC signaling.In case, the reporting periodicity value at a serving cell c forperiodic CQI/PMI is determined by the reference UL/DL configurationvalue configured via the RRC signaling.

FIG. 7 is a flow chart of CQI/PMI reporting between a terminal and abase station according to an exemplary embodiment of the presentinvention. In FIG. 7, it is described based on the case that a terminalis configured with a carrier aggregation (CA) of a TDD based servingcell and an FDD based serving cell; also, aspects of the presentinvention may be applicable when the dual connectivity is established aswell as CA as stated above.

Referring to FIG. 7, a base station transmits, to a terminal, a TDD/FDDCA configuration information indicating the carrier aggregation of anFDD based first serving cell and a TDD based second serving cell. TheTDD-FDD CA configuration information may include the TDD UL/DLconfiguration information of the TDD based second serving cell. The basestation may transmit the TDD-FDD CA configuration information in a RRCsignaling to the terminal.

The terminal applies the carrier aggregation of the FDD based firstserving cell and the TDD based second serving cell based on the TDD-FDDCA configuration information (S710). In this case the first serving cellmay be a Primary serving cell (Pcell), and the second serving cell maybe a Secondary serving cell (Scell). Or the first serving cell may be asecondary serving cell, and the second serving cell may be a primaryserving cell.

The base station transmits a parameter about the periodic CQI/PMIreporting point of time of the first serving cell or the second servingcell. The parameter about the periodic CQI/PMI reporting point of timemay include the periodic CQI/PMI reporting configuration information,and the above described ‘cqi-pmi/ConfigIndex’ (I_(CQI/PMI)). The basestation may receive the parameter in an upper layer signaling such asRRC signaling. Though S720 is illustrated to be conducted after S700 inFIG. 7, S720 may be carried out simultaneously with S700.

The terminal determines the period and the offset for the periodicCQI/PMI reporting of the first serving cell or the second serving cellbased on the parameter about the periodic CQI/PMI reporting point oftime. In this case the terminal may determine the periodicity value andthe offset value based on the parameter (e.g., I_(CQI/PMI)) and Table 4to Table 5. In this case the determination of the periodicity value maybe based on the criteria as described in Tables 6 to 9.

In one example, in case that a primary serving cell is FDD and asecondary serving cell is TDD, the periodicity value for the periodicCQI/PMI reporting of the secondary serving cell may depend on the TDDUL/DL configuration of the corresponding secondary serving cell. In thiscase the periodicity value may be based on the Table 5 which describesthe mapping relationship among I_(CQI/PMI) and N_(pd) and offset(N_(offset,CQI)) for TDD.

In another example, when the primary serving cell is FDD and thesecondary serving cell is TDD, the periodicity value for the periodicCQI/PMI reporting of the secondary serving cell may be based on theabove described Table 4 describing the mapping relationship amongI_(CQI/PMI) and N_(pd) and offset (N_(offset,CQI)) for FDD.

In another example, when the primary serving cell is TDD and thesecondary serving cell is FDD, the periodicity value for the periodicCQI reporting of the primary serving cell or the secondary serving cellmay depend on the TDD UL/DL configuration of the primary serving cell.

The terminal performs a periodic CQI/PMI reporting to the base stationbased on the above determined period and offset (S740). The periodicCQI/PMI reporting may be carried out by mapping information of CQI/PMIin PUCCH and transmitted the PUCCH via the first serving cell or thesecond serving cell. In one example, when the first serving cell is aprimary serving cell, the periodic CQI/PMI reporting of the firstserving cell or the second serving cell may be carried out via the firstserving cell. In another example, in case that the second serving cellis a secondary serving cell and supports PUCCH transmission, theperiodic CQI/PMI reporting of the first serving cell or the secondserving cell may be performed via the second serving cell.

In accordance with an exemplary embodiment of the present invention,when a terminal is configured with TDD-FDD carrier aggregation (or dualconnectivity), that is, even when the TDD/FDD configuration of theprimary serving cell and the secondary serving cell is different, smoothdata transception between a terminal and a base station may be supportedby the periodicity value configuration for the periodic CSI reporting tothe secondary serving cell.

FIG. 8 is a block diagram illustrating a terminal and a base station inaccordance with an exemplary embodiment of the invention.

Referring to FIG. 8, a terminal 800 includes a terminal receiving unit805, a terminal processor 810 and a terminal transmitting unit 820. Theterminal processor 810 also includes a RRC processing unit 811 and a CSIprocessing unit 812. The terminal receiving unit 805 and the terminaltransmitting unit 820 may be implemented as one transceiver or separatetransmitter and receiver, for example. The transmitter and the receiverinclude one or more antennas.

The terminal receiving unit 805 receives a TDD-FDD CA configurationinformation indicating the carrier aggregation of an FDD based firstserving cell and a TDD based second serving cell from the base station850, and forwards it to the RRC processing unit 811. The TDD-FDD CAconfiguration information includes the TDD UL/DL configurationinformation of the second serving cell. Also, the terminal receivingunit 805 receives a parameter about a periodic CQI/PMI reporting pointof time of the first serving cell or the second serving cell from thebase station 850. In this case the terminal receiving unit 805 mayreceive the TDD-FDD CA configuration information and/or the parameterabout the periodic CQI/PMI reporting point of time via RRC signaling ona Primary serving cell (Pcell) from the base station 850.

The RRC processing unit 811 applies the CA configuration of the FDDbased first serving cell and the TDD based second serving cell to theterminal 800 based on the TDD-FDD CA configuration information. In thiscase, the RRC processing unit 811 may configure, based on the TDD-FDD CAconfiguration information, the first serving cell as a primary servingcell (Pcell) and the second serving cell (Scell) as a secondary servingcell at the terminal 800. Or the RRC processing unit 811 may configure,based on the TDD-FDD CA configuration information, the first servingcell as a secondary serving cell and the second serving cell as aprimary serving cell at the terminal 800.

The RRC processing unit 811 may detect the periodicity value and theoffset value for a periodic CQI/PMI reporting of the first serving cellor the second serving cell to forward them to the CSI processing unit812. The above parameter about the periodic CQI/PMI reporting point oftime may include ‘cqi-pmi-ConfigIndex’ (I_(CQI/PMI)). In this case, theRRC processing unit 811 may determine the periodicity value and theoffset value based on the parameter (e.g., I_(CQI/PMI)) and the aboveTables 4 through 5. In this case the above stated criteria predefinedbetween a terminal 800 and a base station 850 in Tables 6 through 9 mayform a basis for determining the periodicity value.

Also, the RRC processing unit 811 may configure, based on the parameterabout the periodic CQI/PMI reporting point of time, the periodic CQI/PMIreporting of the first serving cell or the second serving cell at theterminal 800.

The CSI processing unit 812 generates the CQI/PMI of the first servingcell or the second serving cell, and carries out a periodic CQI/PMIreporting through the terminal transmitting unit 820 based on thedetermined (or detected) periodicity and the offset value. In this casethe terminal transmitting unit 820 may map the periodic CQI/PMIreporting into PUCCH to communicate to the base station 850 on theprimary serving cell or the secondary serving cell.

The base station 850 comprises a base station transmitting unit 855, abase station receiving unit 860 and a base station processor 870. Alsothe base station processor 870 comprise a RRC processing unit 871 and aCSI processing unit 872. The base station receiving unit 860 and thebase station transmitting unit 855 may be implemented as one transceiveror separate transmitter and receiver, for example. The transmitter andthe receiver include one or more antennas.

The RRC processing unit 871 generates a TDD-FDD CA configurationinformation, and forward it to the base station transmitting unit 855.Also the RRC processing unit 871 generates a parameter about theperiodic CQI/PMI reporting point of time of the first serving cell orthe second serving cell, and forwards it to the base stationtransmitting unit 855. The RRC processing unit 871 may receiveinformation for generating the parameter about the periodic CQI/PMIreporting point of time from the CSI processing unit 872. The RRCprocessing unit 871 may determine the periodicity value and the offsetvalue based on the parameter (e.g., I_(CQI/PMI)) and Tables 3 to 4. Inthis case, the determination of the periodicity value may be based onthe above criteria between a terminal 800 and a base station 850 whichare predefined in Tables 6 through 9.

The base station transmitting unit 855 transmits the TDD-FDD CAconfiguration information to the terminal 800. Also, the base stationtransmitting unit 855 sends the parameter about the periodic CQI/PMIreporting point of time of the first serving cell or the second servingcell to the terminal 800. In this case the base station transmittingunit 855 may transmit the TDD-FDD CA configuration information and/orthe parameter about the periodic CQI/PMI reporting point of time via RRCsignaling on a primary serving cell (Pcell) to the terminal 800. In thiscase the RRC signaling may be a RRC connection reconfiguration message.

The base station receiving unit 860 receives, at the DL HARQ timing forthe second serving cell, an ACK/NACK signal in the uplink subframe ofthe first serving cell from the terminal 800. The ACK/NACK signal may bereceived mapped into the PUCCH of the first serving cell.

The CSI processing unit 872 configures the parameter about the periodicCQI/PMI reporting point of time.

Also, the CSI processing unit 872 may perform link adaptation based onthe periodic CQI/PMI reporting by the first serving cell or the secondserving cell received by the base station receiving unit 860, and mayadapt/adjust Modulation and Coding Scheme (MCS) and transmission powerper a given channel.

A base station establishes an RRC connection with a UE through a primaryserving cell (PCell). If the PCell supports a TDD mode and the basestation provides a UE with CA configuration information to configure asecondary serving cell (SCell) supporting an FDD mode, the base stationtransmits an RRC message including the CA configuration informationindicating a TDD-FDD CA. The RRC message may include acqi-pmi-ConfigIndex, which indicates a periodicity (N_(pd)) and anoffset (N_(OFFSET,CQI)) for CQI and PMI reporting with respect to theSCell.

The UE establishes the RRC connection with the base station and receivesthe CA configuration information and the cqi-pmi-ConfigIndex. The UEconfigures a TDD-FDD CA configuration so that the PCell supports a TDDmode and the SCell supports an FDD mode in the UE. When the TDD-FDD CAis configured, the UE determines the periodicity (N_(pd)) and the offset(N_(OFFSET,CQI)) for CQI and PMI reporting with respect to the SCellbased on the above table 5 and the cqi-pmi-ConfigIndex even though thetable 5 is generally used for a TDD cell and the SCell supports an FDDmode. In this CA configuration, the periodicity (N_(pd)) may bedetermined further based on a TDD UL/DL configuration of the PCell. Forexample, periodicity (N_(pd))=1 may be used only when the TDD UL/DLconfiguration is one of 0, 1, 3, 4, and 6, and periodicity (N_(pd))=5may be used only when the TDD UL/DL configuration is one of 0, 1, 2, and6.

If the PCell supports an FDD mode and the base station provides a UEwith CA configuration information to configure a secondary serving cell(SCell) supporting a TDD mode, the base station transmits an RRC messageincluding the CA configuration information indicating an FDD-TDD CA. TheRRC message may include a cqi-pmi-ConfigIndex, which indicates aperiodicity (N_(pd)) and an offset (N_(OFFSET,CQI)) for CQI and PMIreporting with respect to the SCell.

The UE establishes the RRC connection with the base station and receivesthe CA configuration information and the cqi-pmi-ConfigIndex. The UEconfigures an FDD-TDD CA configuration so that the PCell supports an FDDmode and the SCell supports a TDD mode in the UE. When the FDD-TDD CA isconfigured, the UE determines the periodicity (N_(pd)) and the offset(N_(OFFSET,CQI)) for CQI and PMI reporting with respect to the SCellbased on the above table 4 and the cqi-pmi-ConfigIndex even though thetable 4 is generally used for an FDD cell and the SCell supports a TDDmode. Further, when eIMTA is enabled at the serving cell c, the TDDUL/DL configuration of the Scell may be replaced with or referred to aUL/DL configuration value configured via RRC signaling. In case, thereporting periodicity value at a serving cell c for periodic CQI/PMI isdetermined by the reference UL/DL configuration value configured via theRRC signaling.

Once the periodicity (N_(pd)) and the offset (N_(OFFSET,CQI)) aredetermined, the UE reports channel state information of the SCell to thebase station. The UE periodically transmits a channel quality indicator(CQI) for the SCell and/or a precoding matrix indicator (PMI) for theSCell so that the base station determines the channel state of the SCellfor communication with the UE.

While the present invention has been shown and described in connectionwith the embodiments, it will be apparent to those skilled in the artthat modifications and variations can be made without departing from thespirit and scope of the invention as defined by the appended claims.Thus, the present invention is not limited to the foregoing embodimentsand may include all the embodiments within the scope of the appendedclaims.

What is claimed is:
 1. A method of transmitting at least one of aChannel Quality Indicator (CQI) and a Precoding Matrix Indicator (PMI)from a user equipment (UE) to a base station, the method comprising:establishing a Radio Resource Control (RRC) connection with the basestation through a first serving cell, the first serving cell supportinga Time Division Duplex (TDD) mode; receiving an RRC message from thebase station through the first serving cell, the RRC message comprisingcarrier aggregation (CA) configuration information, the CA configurationinformation comprising information of a second serving cell supporting aFrequency Division Duplex (FDD) mode, and the first serving cell and thesecond serving cell being aggregated by a TDD-FDD CA scheme; determininga periodicity (N_(pd)) and an offset (N_(OFFSET,CQI)) based on acqi-pmi-ConfigIndex received from the base station, thecqi-pmi-ConfigIndex being a numerical parameter, the periodicity(N_(pd)) being a periodicity for periodically reporting at least one ofCQI and PMI with respect to the second serving cell, the offset(N_(OFFSET,CQI)) being an offset for periodically reporting the at leastone of CQI and PMI, and the periodicity (N_(pd)) being determinedfurther based on a TDD UL(Uplink)/DL(Downlink) configuration of thefirst serving cell; and periodically transmitting, to the base station,the at least one of CQI and PMI according to the periodicity (N_(pd))and the offset (N_(OFFSET,CQI)) through the first serving cell or thesecond serving cell, wherein the periodicity (N_(pd)) and the offset(N_(OFFSET,CQI)) are determined based on the cqi-pmi-ConfigIndex(I_(CQI/PMI)) shown in Table 1: TABLE 1 I_(CQI/PMI) Value of N_(pd)Value of N_(OFFSET,CQI) I_(CQI/PMI) = 0 1 I_(CQI/PMI) 1 ≦ I_(CQI/PMI) ≦5 5 I_(CQI/PMI) − 1 6 ≦ I_(CQI/PMI) ≦ 15 10 I_(CQI/PMI) − 6 16 ≦I_(CQI/PMI) ≦ 35 20 I_(CQI/PMI) − 16 36 ≦ I_(CQI/PMI) ≦ 75 40I_(CQI/PMI) − 36 76 ≦ I_(CQI/PMI) ≦ 155 80 I_(CQI/PMI) − 76 156 ≦I_(CQI/PMI) ≦ 315 160 I_(CQI/PMI) − 156 316 ≦ I_(CQI/PMI) ≦ 1023Reserved.


2. The method of claim 1, further comprising: when the first servingcell is a primary serving cell supporting the TDD mode, the secondserving cell is a secondary serving cell supporting the FDD mode, andthe TDD UL/DL configuration of the first serving cell belongs to {0, 1,3, 4, 6}, receiving the cqi-pmi-ConfigIndex indicating that theperiodicity (N_(pd)) for the second serving cell is set as
 1. 3. Themethod of claim 1, further comprising: when the first serving cell is aprimary serving cell supporting the TDD mode, the second serving cell isa secondary serving cell supporting the FDD mode, and the TDD UL/DLconfiguration of the first serving cell belongs to {0, 1, 2, 6},receiving the cqi-pmi-ConfigIndex indicating that the periodicity(N_(pd)) for the second serving cell is set as
 5. 4. The method of claim1, further comprising: when the first serving cell is a primary servingcell supporting the TDD mode, the second serving cell is a secondaryserving cell supporting the FDD mode, and the TDD UL/DL configuration ofthe first serving cell belongs to {0, 1, 2, 3, 4, 5, 6}, receiving thecqi-pmi-ConfigIndex indicating that the periodicity (N_(pd)) for thesecond serving cell is set as one of 10, 20, 40, 80, and
 160. 5. Themethod of claim 1, further comprising: receiving information toconfigure enhanced Interference Management and Traffic Adaptation(eIMTA) for the first serving cell; confirming DL reference UL/DLconfiguration of the first serving cell; and receiving thecqi-pmi-ConfigIndex from the base station.
 6. The method of claim 5,wherein, if the UE is configured with the eIMTA for the first servingcell supporting the TDD mode, the TDD UL/DL configuration of the firstserving cell corresponds to DL reference UL/DL configuration.
 7. Themethod of claim 1, wherein the CQI and the PMI are received as channelstate information for the second serving cell, and the CQI and the PMIare included in a Physical Uplink Control Channel (PUCCH), and whereinthe PUCCH being transmitted through the first serving cell or the secondserving cell.
 8. A method of transmitting at least one of a ChannelQuality Indicator (CQI) and a Precoding Matrix Indicator (PMI) from auser equipment (UE) to a base station, the method comprising:establishing a Radio Resource Control (RRC) connection with the basestation through a first serving cell, the first serving cell supportinga Frequency Division Duplex (FDD) mode; receiving an RRC message fromthe base station through the first serving cell, the RRC messagecomprising carrier aggregation (CA) configuration information, the CAconfiguration information comprising information of a second servingcell supporting a Time Division Duplex (TDD) mode, and the first servingcell and the second serving cell being aggregated by an FDD-TDD CAscheme; determining a periodicity (N_(pd)) and an offset(N_(OFFSET,CQI)) based on a cqi-pmi-ConfigIndex received from the basestation, the cqi-pmi-ConfigIndex being a numerical parameter, theperiodicity (N_(pd)) being a periodicity for periodically reporting atleast one of CQI and PMI with respect to the second serving cell, andthe offset (N_(OFFSET,CQI)) being an offset for periodically reportingthe at least one of CQI and PMI; and periodically transmitting, to thebase station, the at least one of CQI and PMI according to theperiodicity (N_(pd)) and the offset (N_(OFFSET,CQI)) through the firstserving cell or the second serving cell, wherein the periodicity(N_(pd)) and the offset (N_(OFFSET,CQI)) are determined based on thecqi-pmi-ConfigIndex (I_(CQI/PMI)) shown in Table 2 TABLE 2 I_(CQI/PMI)Value of N_(pd) Value of N_(OFFSET,CQI) 0 ≦ I_(CQI/PMI) ≦ 1 2I_(CQI/PMI) 2 ≦ I_(CQI/PMI) ≦ 6 5 I_(CQI/PMI) − 2 7 ≦ I_(CQI/PMI) ≦ 1610 I_(CQI/PMI) − 7 17 ≦ I_(CQI/PMI) ≦ 36 20 I_(CQI/PMI) − 17 37 ≦I_(CQI/PMI) ≦ 76 40 I_(CQI/PMI) − 37 77 ≦ I_(CQI/PMI) ≦ 156 80I_(CQI/PMI) − 77 157 ≦ I_(CQI/PMI) ≦ 316 160 I_(CQI/PMI) − 157I_(CQI/PMI) = 317 Reserved 318 ≦ I_(CQI/PMI) ≦ 349 32 I_(CQI/PMI) − 318350 ≦ I_(CQI/PMI) ≦ 413 64 I_(CQI/PMI) − 350 414 ≦ I_(CQI/PMI) ≦ 541 128I_(CQI/PMI) − 414 542 ≦ I_(CQI/PMI) ≦ 1023 Reserved.


9. The method of claim 8, wherein the CQI and the PMI are received aschannel state information for the second serving cell, and the CQI andthe PMI are included in a Physical Uplink Control Channel (PUCCH), andwherein the PUCCH being transmitted through the first serving cell orthe second serving cell.
 10. A method of receiving at least one of aChannel Quality Indicator (CQI) and a Precoding Matrix Indicator (PMI)by a base station, the method comprising: establishing a Radio ResourceControl (RRC) connection with a user equipment (UE) through a firstserving cell, the first serving cell supporting a Time Division Duplex(TDD) mode or a Frequency Division Duplex (FDD) mode; transmitting anRRC message for the UE through the first serving cell, the RRC messagecomprising carrier aggregation (CA) configuration information and acqi-pmi-ConfigIndex, the CA configuration information comprisinginformation of a second serving cell supporting an FDD mode or a TDDmode, and the first serving cell and the second serving cell beingaggregated by a TDD-FDD CA scheme or an FDD-TDD CA scheme for the UE;periodically receiving, from the UE, at least one of CQI and PMI withrespect to the second serving cell, the at least one of CQI and PMIbeing received through the first serving cell or the second servingcell, wherein a periodicity (N_(pd)) and an offset (N_(OFFSET,CQI)) forthe at least one of CQI and PMI are determined based on thecqi-pmi-ConfigIndex, the cqi-pmi-ConfigIndex is a numerical parameter,the periodicity (N_(pd)) is a periodicity for periodically reporting theat least one of CQI and PMI with respect to the second serving cell, andthe offset (N_(OFFSET,CQI)) is an offset for periodically reporting theat least one of CQI and PMI, and wherein, when the first serving cellsupports a TDD mode and the second serving cell supports an FDD mode,the periodicity (N_(pd)) is determined further based on a TDDUL(Uplink)/DL(Downlink) configuration of the first serving cell,wherein, when the first serving cell supports a TDD mode and the secondserving cell supports an FDD mode, the periodicity (N_(pd)) and theoffset (N_(OFFSET,CQI)) are determined based on the cqi-pmi-ConfigIndex(I_(CQI/PMI)) shown in Table 3: TABLE 3 I_(CQI/PMI) Value of N_(pd)Value of N_(OFFSET,CQI) I_(CQI/PMI) = 0 1 I_(CQI/PMI) 1 ≦ I_(CQI/PMI) ≦5 5 I_(CQI/PMI) − 1 6 ≦ I_(CQI/PMI) ≦ 15 10 I_(CQI/PMI) − 6 16 ≦I_(CQI/PMI) ≦ 35 20 I_(CQI/PMI) − 16 36 ≦ I_(CQI/PMI) ≦ 75 40 I_(CQI/PM)− 36 76 ≦ I_(CQI/PMI) ≦ 155 80 I_(CQI/PMI) − 76 156 ≦ I_(CQI/PMI) ≦ 315160 I_(CQI/PMI) − 156 316 ≦ I_(CQI/PMI) ≦ 1023 Reserved.


11. The method of claim 10, further comprising: when the first servingcell is a primary serving cell supporting the TDD mode, the secondserving cell is a secondary serving cell supporting the FDD mode, andthe TDD UL/DL configuration of the first serving cell belongs to {0, 1,3, 4, 6}, transmitting the cqi-pmi-ConfigIndex indicating that theperiodicity (N_(pd)) for the second serving cell is set as
 1. 12. Themethod of claim 10, further comprising: when the first serving cell is aprimary serving cell supporting the TDD mode, the second serving cell isa secondary serving cell supporting the FDD mode, and the TDD UL/DLconfiguration of the first serving cell belongs to {0, 1, 2, 6},transmitting the cqi-pmi-ConfigIndex indicating that the periodicity(N_(pd)) for the second serving cell is set as
 5. 13. The method ofclaim 10, further comprising: when the first serving cell is a primaryserving cell supporting the TDD mode, the second serving cell is asecondary serving cell supporting the FDD mode, and the TDD UL/DLconfiguration of the first serving cell belongs to {0, 1, 2, 3, 4, 5,6}, transmitting the cqi-pmi-ConfigIndex indicating that the periodicity(N_(pd)) for the second serving cell is set as one of 10, 20, 40, 80,and
 160. 14. The method of claim 10, further comprising: transmittinginformation to configure enhanced Interference Management and TrafficAdaptation (eIMTA) for the first serving cell.
 15. The method of claim14, wherein, if the UE is configured with the eIMTA for the firstserving cell supporting the TDD mode, the TDD UL/DL configuration of thefirst serving cell corresponds to DL reference UL/DL configuration. 16.The method of claim 10, when, the first serving cell supports an FDDmode and the second serving cell supports a TDD mode, the periodicity(N_(pd)) and the offset (N_(OFFSET,CQI)) are determined based on thecqi-pmi-ConfigIndex (I_(CQI/PMI)) shown in Table 4 TABLE 4 I_(CQI/PMI)Value of N_(pd) Value of N_(OFFSET,CQI) 0 ≦ I_(CQI/PMI) ≦ 1 2I_(CQI/PMI) 2 ≦ I_(CQI/PMI) ≦ 6 5 I_(CQI/PMI) − 2 7 ≦ I_(CQI/PMI) ≦ 1610 I_(CQI/PMI) − 7 17 ≦ I_(CQI/PMI) ≦ 36 20 I_(CQI/PMI) − 17 37 ≦I_(CQI/PMI) ≦ 76 40 I_(CQI/PMI) − 37 77 ≦ I_(CQI/PMI) ≦ 156 80I_(CQI/PMI) − 77 157 ≦ I_(CQI/PMI) ≦ 316 160 I_(CQI/PMI) − 157I_(CQI/PMI) = 317 Reserved 318 ≦ I_(CQI/PMI) ≦ 349 32 I_(CQI/PMI) − 318350 ≦ I_(CQI/PMI) ≦ 413 64 I_(CQI/PMI) − 350 414 ≦ I_(CQI/PMI) ≦ 541 128I_(CQI/PMI) − 414 542 ≦ I_(CQI/PMI) ≦ 1023 Reserved.


17. The method of claim 10, wherein the CQI and the PMI are received aschannel state information for the second serving cell, and the CQI andthe PMI are included in a Physical Uplink Control Channel (PUCCH), andwherein the PUCCH being transmitted through the first serving cell orthe second serving cell.
 18. The method of claim 5, wherein, if the UEis configured with the eIMTA for the first serving cell supporting theTDD mode, the DL reference UL/DL configuration of the first serving cellfor DL HARQ is selected from among TDD UL/DL configuration {2, 4, 5}.